Speaker
Description
The tensor form factors of the nucleon provide essential information for understanding its internal spin structure. The monopole tensor form factor at $Q^2=0$ is identified as the nucleon tensor charge, which corresponds to the first moment of the leading-twist transverse parton distribution function $h_1(x)$. While transversity has been extensively studied both theoretically and experimentally, other tensor form factors have received much less attention. In this talk, we present recent results for the nucleon multipole tensor form factors calculated within the pion mean-field theory. The framework is based on the effective dynamics arising from spontaneous chiral symmetry breaking and the mean-field description of the nucleon at leading order in the large-$N_c$ limit. We find that the tensor charge ($g_{T}^{u-d}=0.99$) and the tensor anomalous magnetic moment ($\kappa_{T}^{u+d}=7.61$) are dominated by valence quark contributions, whereas the tensor quadrupole moment ($Q_{T}^{u-d}=-7.02$) shows significant sea quark effects. We also explore the dependence of these moments on the soliton size and the pion mass, observing a smooth transition between non-relativistic and relativistic regimes. The results agree well with available lattice QCD data and provide predictions for unmeasured quantities.
| Theoretical or experimental | Theoretical |
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